As an injection apparatus, there is known an apparatus which uses an injection cylinder to drive a plunger pushing out a molding material into a die (for example Patent Literature 1). The speed of the injection cylinder (in other words, the injection speed) is generally controlled by a meter-in circuit which controls a flow rate of a hydraulic fluid supplied to the injection cylinder and/or a meter-out circuit which controls a flow rate of a hydraulic fluid discharged from the injection cylinder. The meter-in circuit or meter-out circuit has a flow control valve and usually is feedback controlled based on the speed of the plunger.
The injection speed exerts a large influence upon the quality of the molded article and is suitably set considering various conditions. For example, the injection speed, in an initial stage of injection, is made a low injection speed which is relatively low in speed in order to suppress entrapment of air by the molding material. After that, it is made a high injection speed which is relatively high in speed for the purpose of for example filling the molding material in the die without delay before solidification of the molding material.